Cutting apparatus for lenses, especially spectacle-glasses



T. G. AULlN July 29, 1952 CUTTING APPARATUS FOR LENSES, ESPECIALLYSPECTACLE-GLASSES Filed April 5, 1945 4 Sheets-Sheet l July 29, 1952 T.G. AULIN 2,604,697

CUTTING APPARATUS FOR LENSES, ESPECIALLY SPECTACLE-GLASSES Filed April'5, 1945 4 Sheets-Sheet 2 July 29, 1952 T. e. AULlN 2,604,697

CUTTING APPARATUS FOR LENSES, ESPECIALLY SPECTACLE-GLASSES Filed April5, 1945 4 Sheets-Sheet 3 July 29, 1952 'r. G. AULIN 2,604,697

CUTTING APPARATUS FOR LENSES, ESPECIALLY SPECTACLE-GLASSES Filed April5, 1945 '4 Sheets-Sheet 4 m iq- 9 #9 INVENTOR f' 7 raAu/J/v PatentedJuly 29, 1952 CUTTING APPARATUS FOR LENSES, ESPE- CIALLYSPECTAGLE-GLASSES Tage Gunnar Aulin, Trollhattan, Sweden, as-

signor to J. P. Brandt Aktiebolag, Stockholm, Sweden, a company ofSweden Application April 5, 1945, Serial No. 586,727 In Sweden July 25,1944 6 Claims.

In hitherto known cutting apparatus for spectacle-glasses, the rotatablesupporting table for the lens is provided with a central, yielding pin,which thus marks the axis of rotation. Spectacle-glasses, when deliveredfrom the maker are usually provided with a coloured mark, indicating theoptical center of the glass and serving for guidance in placing theglass on the supporting table. Such simple devices are obviouslyinadequate to enable the glass to be out in the right way, especiallywhen some degree of decentering is desired. In order that the wearer ofthe eye-glasses or spectacles shall not feel some discomfort, thedeviations from the prescribed placing of the glasses must not exceedcertain tolerances, which, especially for powerful glasses, are verysmall.

One object of the present invention is to facilitate a correct cuttingof the lens, that is, to provide means for determining the opticalcenter of the lens (in the case of astigmatic glasses, the

positions of the cylinder axes) in the required ably rotatablesupporting table is provided with a central recess or bore for thetransmission of a pencil of rays, produced by a projection device,through a lens arranged on said table whereby the position of theoptical center (or cylinder axis) of the lens relatively to'theedge-line or contour of the lens can be determined.

The accompanying drawings illustrate some embodiments of the invention.

Figure l is a verticalelevation, partly in section, of anapparatusembodying the invention.

Figure 2 is a section on the line 11-11 in Figure 1.

Figure 3 is a vertical section on the broken line IIIIII in Figure 1.

Figure 4 is a detail of Figure 1 on a larger scale.

Figures 5 and 6 show diagrammatically in vertical elevation and planView respectively, parts of another embodiment of the invention.

Figures '7 and 8 illustrate a side view'and a horizontal view,respectively, of a further embodiment, and

Figures 9 and 10 illustrate a sidevie'w and a sectional view on the line'X- -X 01 F g. 9 of the device of Figs. '7 and 8 and including theoptical system.

According to Figures 1-4 the apparatus comprises a base plate I carryinga frame structure 2. Arranged in the lower part 2a of the frame 2 is aprojection device comprising a source of light 3 (a lamp), a ruled discor reticle 4 and an optical system, here shown in the form of a lens 5mounted in a holder 6 in a tube 1 forming part of the member 2a. Thereticle 4 may consist of a black disc of glass having a cross, a seriesof crossing lines and circles or some other index engraved in its centerto allow the rays of light to pass therethrough. The reticle 4 ismounted in a holder 4a which by means of a pin 4b attached to a ring 40and guided in a groove Ad in the wall of the tube 1 may be displacedvertically within said tube. Thus, by screwing the ring to the level ofthe reticle may be adjusted.

Mounted in the upper part 8 of the frame 2 coaxially with the opticalaxis of the optical system 3, 4, 5 is a tube 9 containing a lens [0, ahair cross plate H and a magnifying glass system'or ocular i2 axiallydisplaceable in'th'e tube 9. The projection device 3, 4, 5 transmits apencilof rays which is caught in the tube 9, where the rays arerefracted by means of the lens It] so as to obtain an image of thereticle cross 4, which is viewed through the magnifying glass l2. Thecenter of the hair cross H is arranged coaxially with that of thereticle 4.

Bolted to the base plate I is a vertical standard l3 having a horizontalbranch l3a in which a supporting table is is mounted rotatably. Thetable it carries a seat or ring It of rubber or other soft materialadapted to support the lens or glass IT to be cut. The lens I! is heldfirmly forced against the ring l6 by means of a holder or sleeve l8actuated and carried by a spring 19 attached to the part 8. The table Mhas a central bore or recess l5 allowing the pencil of rays from theprojection device 3, 4, 5 to the tube 9 to pass through the lens I! ontheir way to the hair cross II and the magnifying glass I2. It is easilyunderstood that if the lens I1 is introduced eccentrically into the pathof rays it will cause the image of the reticle 4 to be decenteredrelatively to the hair cross I I. In order to center the optical axis ofthe lens 11 in said path of rays the lens is displaced on its seat [6until the central index of the reticle 4, when observed through themagnifying glass l2, coincides with the hair cross H. After centering,the lens is fixed in the holder l8.

The table l4 may be rotated by suitable means. To this purpose thedrawing shows that the table is provided with a worm gear 20 adapted tomesh with a screw 2| which is journalled rotatably in bearing brackets22 attached to the branch [3a. The screw 21 may be rotated by means of ahandle 23.

The table l4 also supports an annular pattern or templet 24 having anexternal contour l'la (see dash lines in Figure 3) corresponding to theintended contour of the lens 11 to .be out. Of course, this pattern isarranged changeably so that it may be replaced by a pattern of any-otherdesired contour. The inner periphery of "the annular pattern engages acorresponding seat on the table l4 so that the pattern is firmly held onthis table. Said seat is arranged centrally-relatively to the axis ofrotation of the table.

The cutting device may consist of a cutting diamond 25 mounted in aholder 26 which at 2'! is pivoted to a lever 23 swingable on a bolt 29or the like which is attached to the part 8. The lower end 28a of thelever 28 engages and ,is guidedby the outer edge of the pattern .24.

It should be noted-that'the axis of the bore i is coaxial to the axis ofrotation of the table M. Hence, if the lens I! has been centered in thepath of raysin the manner described the optical center (or axis) of thelens is also centered relatively to said axis of rotation and thus tothe pattern 24 which is arranged centrally on the table l4. When, inthis position, the lens is cut by the diamond 25 upon rotation of thetable M. the new contour of the lens will coincide with or be parallelto the contour Ila and the optical center of the lens will becenteredfin this cut contour of the lens in the intended manner.

In some cases, a certain decentering of the optical center of the lensin the contour of the lens is desired. To this purpose, the frame 2 isarranged displaceably in a guide groove I a in the base plate. Thedegree of displacement, and thus of the decentration, can be read on anonius scale 3| on the base plate by means of an index on the frame 2.After this displacement the lens H is centered in the path of rays inthe manner described, whereupon the lens is out by rotating the table14. It is understood that in this mannerthe optical center of the lenswill be decentered in the cut contour to a degree corresponding to thedisplacement of the projection device relatively to the table It.

Should the intended shape of the cut lens deviate from acircularcontour, the table i 4 and the pattern 24 must be adjusted, beforecentering the lens I! inthe pencil of rays, so that decentering in thecontour of the lens in the required direction is obtained.

Instead of thus displacing the pencil of rays, the table l4 may bedisplaced together with the appertaining pattern. Also in this case thesame possibilities of decentering can be effected.

In order to obtain distinct images of the reticle 4 when centeringastigmatic glasses, the apparatus may be provided with a diaphragm whichcan be introduced into the pencil of rays, and which can be placedeither in front of or behind the lens l1. Figures ,1 and 4 show anexample of such a diaphragm arrangement comprising a plate 32 whichisrotatable on a pivot 35 attached to a bolt 36 or the like carried by thepart 8. This plate has a small aperture 34 acting as a diaphragm whenthe plate 32 is swung into the center of the path of rays passing to theocular l2 (it being assumed that the holder I8 is lifted 4 to allow thismovement). The plate also carries a lens 33 for the purpose indicatedbelow.

So-called bifocal glasses consist of two lens parts with different fociand usually also different optical centers. One of these parts isintended for seeing at a distance, and the other for seeing at closequarters. In view of the convergence of the eyes when seeing at closequarters, it is desirable, in order that the spectacles or eye-glassesshall have the distance between .the optical .iCQlltBIS indicated byoculists in their prescription that the optical centers of the nearparts of the bifocal glasses should lie closerto one another than theoptical centers of the distant parts. Hitherto as a rule, in theordinary types-of bifocal glasses, the connecting linebetween theoptical centers of the distant and near parts has had an inclination atan angle of '5" to the symmetrical plane of the head of the personwearing the glasses. But, as the distances between these optical centersvary very considerably (from-scarcely any distance at all to a distanceof about 10 mm.) it is obvious that this inclination should be varied.When the distance between the optical centers of the distant and nearparts has been measured with the aid of a suitable apparatus, thenecessary turning can be computed by a simple calculation.

If a bifocal glass is placed on the supporting table E4 in the deviceshown in Figures 1 to 3, a distinct image will, for example, be obtainedin the ocular I2 through the distant part, whilst the image viewedthrough the near part will be blurred. The blurring, however, can beeliminated by placing in front of the "near part a negative lens (forexample the lens 33 in the rotatable plate 32, Figures 1 and 4) of suchpower that the image-will be brought out in quite sharp relief alsothrough this part. In this way a bifocal glass produces two images,which, as we know, fall on the hair-cross in the tube 9. The hair crossis arranged in the plate II as shown in Figure 1. By turning the ocularI2 the required number of degreesrelatively to the symmetrical planeofthe lens contour, and then (by turning the lens H) causing the twoimages to fall on one of the axes of the hair-cross, the desiredposition of the two lens parts relatively to the lens contour can beobtained.

Another important condition in bifocal glasses is that the lines, ofdemarcation between the distant and near parts of the glasses should lieat .a level, relatively to the so-called zero-line (av-line) .of thespectacles, approximately corresponding to a line drawn across theattachments of thespectacle rims (the nose-bridge).

For this purpose, the device in accordance with the invention may beprovided with two oculars l2 and 31 placed on a revolving disc 38, asshown quite diagrammatically in Figure 5. One of these oculars, 31, hassuch a focus that one can simultaneously observe through it the line ofdemarcation and an index disc (reticle) or ruled disc 40 (Fig. 6) placedin the recess or bore l5 of the table l4, and provided with a graduatedscale, the zero line of which crosses the axis of rotation of the table.The distance between the line of demarcation and the .zero axis, which(depending on the different position in which a pair of spectacles isworn by different persons) varies in different cases, can then easily beadjusted in the same way for both spectacle-glasses with the aidv of theruled disc or index 40 in the recessl5.

The lenses required during the cutting of the bifocal glasses can beintroduced at a suitable place in the path of the rays in front of orbehind the glass H, which is to be cut. As already described, Figure 4shows one example of arranging such a lens 33, preferably arrangedinterchangeably so as to be replaceable by lenses of different kinds andstrengths. By turning the ring 40 and thus adjusting the level of thereticle 4 the image viewed through the distant part can, for example, befocussed in sharp relief, the power of the glass being at the same timeascertained in known manner. As the difference between the distant andnear part may vary from 0.5 to 5 dioptrics, several extrainterchangeable lenses 33 will, in all cases, be required in order toobtain a distinct image through the near part. The number, however,'canbe restricted to ten, in which case the difference between the differentpowers of the lenses in the series will be 0.5 dioptrics. It is in factunnecessary to attain perfect distinctness: some slight blurring of theimage is permissible in'focussing.

Figures '7 and 8 show a modification of the apparatus described withreference to Figures 1 to 3. The principal idea underlying theconstruction shown in Figures 7 and 8 is that the decentering of theoptical center of the lens or glass I1 is efifected by decentering thepattern instead of the path of rays or the table l4. According toFigures 7 and 8 the pattern is arranged on a rotatable supportseparately from the support or table M for the lens H. The holder 26 forthe cutting tool 25 is arranged swingably on a shaft 4| guided slidablyin axial direction in brackets 42 and 43 carried by the part I311. Thebracket 43 may be provided with a pin 44 engaging a longitudinal groove45 in the shaft 4| so as to prevent said shaft from rotating. Attachedto the end of shaft 4| by means of a nut 46 is a rod 4'5 carrying a setscrew 49, the end 48 of which engages the periphery of the pattern ortemplet 5|. The screw 49 may be provided with a scale so that theadjusted position of the screw may be read by means of an index finger5|).

The pattern 5| has apertures 5|a for guide pins attached to a slideblock 52 carrying the pattern. The pattern is secured to this block bymeans of a screw 56 anda wing nut 51. The block 52 is slidably mountedin a supporting guide 53 resting on and attached to a table 6| providedwith a worm gear 60 adapted to mesh with the screw 2| which drives thetables l4 for the lens It is clearly seen that when the screw 2|a isrotated both tables l4 and 6| will rotate and the tool 25 will cut thelens I! along a contour Elb corresponding to the contour of the pattern5|.

In order to indicate the relative position of the block 52 and the guide53 the latter has a scale 59 while the block 52 has an index 58. Whenthe index 58 registers with the -1ine of the scale 55, as shown inFigure 7, the pattern is centered to the axis of rotation of the table6|. Thus, if the optical center of the lens I! is centered on the tableM in the manner described, the said optical center will be centered inthe contour cut by the tool 25; If a decentering is desired the pattern5| is decentered relatively to the axis of table 6| by means of anadjusting screw 54 which may be rotated by a knob 55 so as to displacethe block 52 in the guide 53 to the. desired degree indicated on thescale 59. When the tables GI and I4 now are rotated with the pattern 5|in this decentered position the tool should be understood that thisresult is achieved without decentering the lens' itself, said lensalways lying centered relatively to the axis of the table l4 and of theoptical axis of the projection system, whilst the diamond 25 moveseccentrically in relation to both these axes. The advantage of thisalternative procedure is that it affords facilities for causing theglass or lens I! to rotate before cutting, in order, by viewing theimage falling on the hair cross in the tube 9, to determine whether thelens I"! actually lies exactly centered in relation to the axis of theprojection system or that of the support l4. The lens ll will liecentrally when the image of the reticle 4 falling on the index disc orhair cross lies constantly still despite the rotation of the lens.

If it is desired to cut the lens or glass smaller or larger than thepattern an adjustment is made of the screw 49 engaging the periphery ofthe pattern. Such adjustment will cause a displacement of the cuttingtool 25 relatively to the center of the glass so that the tool will outalong a contour |lb lying at the desired radius.

Figures 7 and 8 show how the pattern may be decentered in one directionby means of the screw 54, 55. If necessary, however, a decentration mayalso be efiected in a direction perpendicularly to the first mentioneddirection by allowing the block 52 to slide in a further guideperpendicular to the guide 53. 7

Figures 9 and 10 show the embodiment of Figs. 7 and 8 but combined withthe optical system such as shown in Fig. 1. In these views the membersidentified by identical reference numerals are the same as those inother views, whereas members 8', I3, l3a' and 22a correspond to parts 8,l3, |3a and 22 of Figures 1 and 7 as will be apparent from the drawings.

The invention is not limited to any particular form of construction: itmay be executed in many different ways. The essential feature of theinvention is that the lens or glass which is to be cut is placed on thesupporting table with the aid of a pencil of rays passing through thelens, whereby the defects inevitably entailed by the hitherto usualcutting methods with a mechanical marking of the lens are completelyeliminated, and the lens can be adjusted in a perfectly cor rect manneron the supporting table before cutting. The invention, of course, is notconfined to cutting apparatus in which the cutting is effected by adiamond: it is applicable also to cutting effected in other ways, e. g.in grinding machines by means of a rotating grinding wheel or any otherkind of cutting or grinding tools.

What I claim is:

1. In a cutting apparatus for lenses, the combination of a rotatablelens holder for a lens to be cut, a rotatable pattern holder for apattern template according to which said lens should be cut, therotational axes of said lens holder and said pattern holder beingmutually parallel and spaced at a fixed, predetermined distance fromeach other, means for synchronously rotating said lens holder andpattern holder, a movable feeler for engaging the edge of. a patterninserted in said pattern holder, a cutting toolcontrolled by said feelerfor cutting a lens inserted in said lens holder, optical means forcentering the lens to be out when inserted in said lens holder, so thatthe optical axis of said lens will coincide with the rotational axis ofthe lens holder, said optical means comprising a projecting device forprojecting a narrow pencil of rays along the rotational axis of saidlens holder, a first reticle device in the path of said pencil-of rays,an aperture in said lens holder covered by the lens insertedin saidholder, a second reticledevice in said path, an ocular through which theimages of both said reticle devices can be viewed superimposed oneupon'the other, whereby coincidence of the two images indicates correctcentering 'of said lens, mechanical means for centering the patterninserted in said pattern holder so that apredetermined axis of saidpattern will coincide with the rotational axis of said pattern holder,displacing means for varying the relative space between the optical axisof said lens and the predetermined axis of said pattern, said displacingmeans comprising an adjusting screw and a scale foraccuratelymeasuringthe amount of such variation, for the purpose ofensuring that said last mentioned relative space will differ from saidpredetermined relative space between said rotational axes of said lensholder and said pattern holder during the cutting operation.

2. In a cutting apparatus for lenses, a rotatable lens holder for thelens to be out, a rotatable pattern holder for a pattern templateaccording to which said lens is to be cut, the rotational axes of saidlens holder and said pattern holder being parallel and arranged at afixed predetermined relative distance, means for synchronously rotatingsaid lens holder and said pattern holder, a movable feeler for engagingthe edge of a pattern inserted in said pattern holder, a cutting toolcontrolled by said feeler for cutting a lens inserted in said lensholder, optical means for centering the lens to be cut wheninserted insaid lens holder, so that the optical axis of the lens will coincidewith the rotational axis of the holder, mechanicalmeans for centering apattern inserted in said pattern holder so that a predetermined axis ofsaid pattern will coincide with the rotational axis of said patternholder, displacing means for producing relative displacement between theaxis of said lens support and said pattern, said displacing meanscomprising an adjusting screw and a readable scale for accuratelymeasuring the amount of such displacement, for the purpose of causingthe relative distance between-the optical axis of the lens and saidpredetermined axis of the pattern to difier from the distance betweensaid rotational axes of said lens holder and said pattern holder duringthe cutting operation.

3. In a cutting apparatus for lenses, a base plate, a first framestructure carrying a rotatable pattern holder and a rotatable lensholder, the axes of rotation of said holders being laterally displacedand mutually parallel, a secand frame structure mounted on said baseplate, said second frame structure carrying an optical system fordetermining the optical axis of a lens inserted in said lens holder ofsaid first frame structure, means for synchronously rotating said lensholder and said pattern holder, a movable ieeler arranged to bearagainst the periphery of a pattern inserted in said pattern holder, acutting tool controlled by said feeler for cutting a lens inserted insaid lens holder, and means for displacing said pattern holder relativeto the rotational axis thereof, said means including a scale and anindex for determining the amount of such displacement.

4. A cutting apparatus for lenses according to claim 3 comprising aguide firmly mounted relative to the rotational axis of said patternholder, a slide block slidably arranged in said guide, an adjustingscrew for controlling the sliding of said slide block in said guide, ascale and an index for measuring the relative position of said slideblock relative to said guide, said pattern holder being mounted on saidslide block.

5. A cutting apparatus for lenses according to claim 3 in which saidsecond frame structure has a lower part beneath said lens holder carriedby said first frame structure, and an upper part above said lens holder,said lower part carrying a source of light, a lens system and a firstreticle, all belonging to said optical system, and said upper partcarrying a second reticle and an adjustable ocular for viewing theimages of both reticles superimposed one upon the other, means for thelongitudinal displacing of said first reticle along its optical axis, adiaphragm with a narrow aperture and means for introducing saiddiaphragm into the path of light between said lens holder and saidsecond reticle, for the purpose of sharpening the image of said firstreticle.

6. A cutting apparatus according to claim 3, in which said second framestructure has a lower part beneath said lens holder carried by saidfirst frame structure, and an upper part above said lens holder, saidlower part carrying a source of light, a lens system and a firstreticle, all belonging to said optical system, and said upper partcarrying a second reticle and an adjustable ocular for viewing theimages of both reticles superimposed one upon the other, means forlongitudinally displacing said first reticle along its optical axis, adiaphragm with a narrow aperture, said diaphragm being further providedwith an aperture for lenses of dilferent strength to be insertedtherein, and means for introducing said aperture into the path of lightbetween said lens holder and said second reticle for the purpose ,ofobtaining a, sharp image of said first reticle on inserting a bifocallens into said lens holder.

TAGE GUNNAR AULIN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,042,346 Henle Oct. 22, 19121,581,883 Steinle Apr. 20, 1926 1,873,526 Allen Aug. 23, 1932 1,984,121Drescher Dec. 11, 1934 2,341,201 Ballard Feb. 8, 1944 FOREIGN PATENTSNumber Country Date 266,767 Great Britain Mar. 7, 1927 487,611 GreatBritain June 23, 1938

